And one of the main architects of the constitution - former French President Valery Giscard d'Estaing - made an emotional appeal to the people of France in a speech to the German parliament just before its vote on Friday.

The campaign has been overshadowed by a gloomy mood brought on by years of faltering growth and unemployment of around 10%.

Treaty rejectionists are also ahead in the Netherlands, which will hold its referendum on Wednesday.

The EU constitution has to be ratified by all 25 member states to become law.

France is the second EU member to hold a referendum on the document. Spain's referendum resulted in a "Yes" vote, which was then ratified by both houses of parliament.

The treaty aims to streamline decision-making in the enlarged EU of 25 nations.